Scavenging two-stroke engine



Feb. 15, 1938. KE R 2,l.08,-576

SCAVE'NGING TWO-STROKE ENGINE Filed May 3, 1935 Patented 15, 1938 I I i I UNITED sTATEs PATENT OFFICE SCAVENGING TWO-STROKE ENGINE Alfred Bokemiiller, Gaggenau, Germany, assign or to Daimler-Benz Aktiengesellschaft, Stilt gart-Unterturkheim, Germany Application May a, 1935, Serial No. 19,140

12 Claims. (Cl.123-65) Two stroke combustion power engines with ment of liberation of the slots e1, their continuacontinuous current scavenging have already been tion directing the scavenging current which proposed generating simultaneously a scavenging leaves these ports, towards the cylinder axis, at current which enters radially into the cylinder, the same time directing it upwardly. As shown proceeding in an axial way, and a rotary scavin Figs. 2 and 5, the ports er and e: are arranged 5 enging current which enters tangentially. This in staggered relation to one another so that they offers, however, the disadvantage that the scavfollow one another alternately in the circumferenging current entering radially and proceeding ential direction. inan axial way towards the exhaust which is to The exhaust outlet is provided in the cylinder scavenge the inside core of the cylinder space, is head and the outflow of the exhaust gases is 10 too much subjected to the centrifugal effect of controlled by means of a P pp v lv 111 wn the rotary scavenging current, getting into its in Fig. 1, by a rotary valve a: as shown in Fig. 2 grip, whereby the scavenging of the inside core ,or by means of a sleeve valve a: which uncovers sufiers. a ports a as shown in Fig. 3.

The invention avoids this disadvantage, setting The mo e of Operation is a follows: 1 15 first of all the scavenging current free, which During the downstroke of the piston the upper has a radial direction, and proceeds in an axial r w of ports e1 is first uncovered as shown in way towards the exhaust and then the scaveng- Fig. 1. By th s means the scavenging current ing current enters tangentially, whilst the interor currents a: are set up w h, after bein ruption of the scavenging currents, especially, flected by the bottom of the piston, flow axially 20 proceeds in a reversed direction. By these means towards the exhaust outlet, pushing the burnt a certain time is allowed for the axial scavenggases to the exhaust d towards e Cylinder ing current to develop itself prior to the produc- W lls wi h n PWfl fi directifln 0f tion of the rotary scavenging current, so that the As soon as according to 2 e lower series 5 whirling gases are partly pushed towards the of ports c: has been opened, the effect of the exhaust, and partly towards the cylinder walls. lower series of slots, possessing conveniently a The gases collecting themselves at the cylinder rgercross sectionI Prevails and a'helical Scavwalls are now taken up by the scavenging curne current 11 aris y the h oc ty o rent starting in a rotary way, respectively prothe intake current the current receives a conceeding helically, and are pushed towards the siderable centrifugal power so that the same does 30 exhaust. After interruption of the turning curnot get disturbed in any way by thescavenging rent a sturdy axial whirling current can once current e t r g through the pp slots 1; 0n

more be produced. the contrary the same passes along the cylinder In the drawing: wall in an appropriate form, in the shape of a Figs, 1 to 3 show a vertical section through the sturdy edge l ye Hereby it can partially also -3 5. upper part of thecylinder of an internal come put in nin vem n y h p r l bustion engine according to the invention in scavenging current 1 or the same can eventually three characteristic stages of the scavenging also subsist as a partial core-current xo, so far P as this is admissible by the arrangement of the 40 Fig. 4 is across section on the'line 4-4.1n Fig. admission ports. As a rule, however, the air 40 2, and I entering at eiwill be entirely diverted-from the Fig. 5 is a diagrammatic view on a larger scale tangential current 1! towards the cylinder walls, of'the portion of the cylinder in the region of as shown by the example, flowing in a more or the ports. less axial direction or in a helical line towards The admission steered by the piston takes the exhaust port. 45

place, on the one side, by the admission ports- When the piston is going up, another sturdy e1, directed radially towards the cylinder axis scavenging of the cylinder core takes place, after and in an oblique way towards the bottomof the closing the lower slots er, the rotary scavenging piston K, and, on the other side, by the lower current .11 losing by its effect and the original core admission ports ea, convemently directed in a. currentxis developing itself anew. q 50 somewhat oblique way towards the above, which The invention is especially designed for .Diesel join tangentially the cylinder. The bottom of engines, respectively for air compressing mathe piston is hereby conveniently provided with chines. The same can of course also be used for an annular trough Kl. on the upper face of the mixture-compressing machines according to the piston, the limitation of which forms at the mo-' purpose of the design. Instead of the piston 5 fleeting means adapted to co-operate with said radial ports for guiding upwardly in the axial direction of the cylinder scavenging air admitted through the radial ports prior to the uncovering of the tangential ports by the piston during the downstroke of the latter and subsequent to the covering of the tangential ports by the piston during its upstroke and an exhaust outlet at the upper end of the cylinder.

2. In a two stroke internal combustion engine, in combination, a cylinder having a series of upwardly inclined tangential ports at the lower end thereof, a piston reciprocating in the cylinder and adapted to uncover the said ports for admitting scavenging and charging air to the cylinder so as to flow in a helical current around the cylinder, said cylinder having a series of downwardly .inclined radial ports above said first-mentioned ports and the piston end having a trough therein with the bottom thereof sloping downwardly from the periphery of the piston and then upwardly towards the centre of the piston adapted to cooperate with said radial ports for guiding upwardly in the axial direction of the cylinder scavenging air admitted through the radial ports prior to the uncovering of the tangential ports by the piston during the downstroke of the latter and subsequent to the covering of the tengential ports by the piston during its upstroke and an exhaust outlet at the upper end of the cylinder.

3. In a two stroke internal combustion engine, in combination, a cylinder having a series of upwardly inclined tangential ports at the lower end thereof. a piston reciprocating in the cylinder and adapted to uncover the "said ports for admittingscavenging and charging air to the cylinder so as to flow in a helical current around the cylinder, said cylinder having a series of downwardly inclined radial ports above said first-mentioned ports and the piston end having a plurality of depressions therein with the bottoms thereof sloping downwardly from the periphery of the piston and then upwardly towards the centre of the piston adapted to co-operate with said radial ports for guiding upwardly in the axial direction of the cylinder scavenging air admitted though the radial ports prior to the uncovering of the tangential ports by the piston during the downstroke of the latter and subsequent to the covering of the tangential ports by the piston during its upstroke and an exhaust outlet at the upper end of the cylinder.

4. In the method of working an internal commentioned body of air and subsequently inter- 5. In a two stroke internal combustion engine,

in combination, a cylinder having a series of upwardly inclined tangential ports at the lower end thereof, a piston reciprocating in the cylinder and adapted to uncover said ports for admitting scavenging and charging air to the cylinder so as to flow in a helical current around the cylinder, said cylinder having a series of downwardly inclined radial ports above said first mentioned ports and alternating therewith circumferentially and the piston end having deflecting means adapted to co-operate with said radial ports for guiding upwardlyin the axial direction of the cylinder scavenging air admitted through the radial ports prior to the uncovering of the tangential ports by the piston during the downstroke of the latter and subsequent to the covering of the tangential ports by the piston during its upstroke and an exhaust outlet at the upper end of the cylinder.

6. In a two stroke internal combustion engine,

end thereof, a piston reciprocating in the cylinder and adapted to uncover saidports for admitting scavenging and charging air to the cylinder so as to flow in a helical current around the cylinder, said cylinder having a series of downwardly inclined radial ports above said first mentioned ports and alternating therewith circumferentially and the piston end having a trough therein with the bottom thereof sloping downwardly from the periphery of the piston and then upwardly towards the centre of the piston adapted to co-operate with said radial ports for guiding upwardly in the axial direction of the cylinder scavenging air admitted through the radial ports prior to the uncovering of the tangential ports by the piston during the downstroke of the latter and subsequent to the covering of the tangential ports by the piston during its'upstroke and an exhaust outlet at the upper end of the cylinder.

7. In a two stroke internal combustion engine, in combination, a cylinder having a series of upwardly inclined tangential ports at the lower end thereof, a piston reciprocating in the cylinder and adapted to uncover the said ports for admitting scavenging and charging air to the cylinder so as to flow in a helical current around the cylinder, said cylinder having a series of downwardly inclined radial ports above said firstmentioned ports and having a larger cross-section than the tangential ports and the piston end having deflecting means adapted to co-operate with said radial ports for guiding upwardly in the axial direction of the cylinder scavenging air admitted through the radial ports prior to the uncovering of the tangential ports by the piston during the downstroke of the latter and subsequent to the covering of the tangential ports by the piston during its upstroke and an exhaust outlet at the upper end of the cylinder.

8. In a two stroke internal combustion engine, in combination, a cylinder having a series of inlet ports at one end thereof for admitting scavenging air to the cylinder, said inlet ports being arranged and directed to cause the air to flow in an 4 tial ports prior to cutting off the flow through the axial stream through the cylinder, said cylinder having further inlet ports at the'said end of the cylinderfor admitting additional scavenging air to the cylinder, said further inlet ports being arranged anddirected to cause the additional scavenging 'airto flow in a helical path through the cylinder, an exhaust outlet at the other end of the cylinder and controlling means forcontrolling the flow ofscavenging air through said ports, said controlling means cd-Operating with the ports so as to admit scavengingair through the first-mentioned ports initially and through the second-mentioned ports subsequently.

9. In a two-stroke internal combustion engine, the combination as set forth in claim 8, in which the controlling means for controlling the flow of scavenging air through the ports cuts off the flow of scavenging air through the second-mentioned ports prior to cutting oiT the flow through the first-mentioned portsv 10. In a two-stroke internal combustion engine,

in combination, a cylinder having a series of tangential inlet ports in proximity to one end thereof, for admitting scavenging air to the cylinder to flow in a helical stream in the cylinder,

said cylinder having a series of radial inlet ports in proximity to the said end of the cylinder for admitting additional scavenging air to the cylinder, deflecting means in the cylinder adapted to co-' operate with said radial inlet ports for deflecting the scavenging air admitted through the radial ports to flow in an axial stream in the cylinder and controlling means co-operating with said tangential and radial inlet ports so as to admit scavenging air initially through the radial inlet ports and subsequently through the tangential ports and to out 01f the flow through the tangenradial ports,.said cylinder having exhaust outlet openings at the end of the cylinder remote from the inlet ports.

11. In a two stroke internal combustion engine, in combination, a cylinder having a series of tangential inlet ports at the lower end thereof,

for admitting scavenging air to the cylinder to flow in a helical stream in the cylinder, said cylinder having a series of radial inlet ports at the same end of .the cylinder for admitting additional scavenging air to the cylinder, a piston reciprocating in the cylinder and adapted to co-operate with said tangential and radial inlet ports so as to admit scavenging air to the cylinder initially through the radial .inlet ports and subsequently through the tangential inlet ports and to out oil the flow through the tangential ports prior to cutting ofi the flow through the radial ports, said piston having a deflecting surface adapted to cooperate with the radial. inlet ports for deflecting the scavenging air admitted through the radial ports to flow in an axial stream in the cylinder, said cylinder having exhaust outlet openings at the upper end of the cylinder.

12. -In a two stroke internal combustion engine, in combination, a cylinder having a series of tangential inlet ports in proximity to the lower end thereof for admitting scavenging air to the cylinder to flow in a. helical stream in the cylinder, said cylinder having 'a series of radial inlet ports in proximity to the lower end of the cylinder located above said tangential portsv and extending at an angle situated in a plane passing i through the axis of the cylinder with respect to said tangential ports, so that the directional lines of the said ports intersect one another in the said plane inside the cylinder, a piston reciprocating in the cylinder and adapted to uncover the said inlet ports for controlling the admissionof scavenging air to the cylinder, said piston having deflecting means thereon adapted to co-operate with the radial inlet ports for causing the air admitted through the radial inlet ports to flow in an axial stream through the cylinder and the cylinder having an exhaust outlet at the upper end thereof.

ALFRED BOKEMULLER. 

